Of the sexual dimension of the neck of the giraffe

IThese are subjects that the columnist must approach with caution. Highly flammable, preceded by centuries of controversy, they place us precariously on the shoulders of giants. But how can you resist an article from the magazine Science which ensures the resolution of a fascinating, ancestral question, which brings together the child and the scientist: the origin of the long neck of the giraffe.

For lack of a satisfactory hypothesis, the Greeks had kicked into touch: her dress and her appearance testified to the union of a leopard and a camel. Not convinced, Carl von Linné (1707-1778) named it anyway, in 1758, Giraffa camelopardalis, its current scientific name, borrowing from Arabic zirafa.

Which didn’t settle the neck issue. Past various eccentric assumptions, the origin of its dimension symbolized the confrontation of two schools. By order of entry on stage, Jean-Baptiste de Lamarck (1744-1829) drew first. For him, the giraffe, eager to reach the leaves located in height, had stretched its neck and transmitted this acquired character to its giraffes. And so on for thousands of generations. No, Charles Darwin (1809-1882) answered him a few decades later: like humans, giraffes are more or less tall, and the tallest have been favoured, have lived longer, benefited from greater descent. A model of ” natural selection “.

Read also: Giraffes threatened with “silent extinction”

In any case, both agreed on the central role of access to food. In 1996, however, two South African zoologists, Robert Simmons and Lue Schippers, proposed another hypothesis: that of sexual selection. To curry favor with the females, the males clash with their necks. Like the large antlers of deer, the disproportionate cervical vertebrae would have been favored. As proof, the neck of the males is larger. To this theory called “necks for sex”many replied that the sexual dimorphism of giraffes was nothing exceptional and invited the two revolutionaries to return to comb the animal.

Close ancestor of the okapi

The article published in Science, Thursday, June 2, by a Sino-Swiss team, however, takes up this theory. It is based on the discovery, in 1996, by Professor Jin Meng, of the Chinese Academy of Sciences, of a 16.9 million year old fossil in the Xinjiang desert: a skull and four vertebrae. . “He immediately saw that it was a strange animal, but he first thought of a bovid”, says Shiqi Wang, first author of the article. Paleontologists continued excavations, accumulated material and it was in 2015 that a major study was launched. “A colossal job” gathering “geochemistry, stress analysis, analysis of cranial appendages in histology, analysis of internal cranial structures”, explains Loïc Costeur, curator at the Basel Natural History Museum. He took care of the inner ear, an element that proved essential to the attribution of the fossil to the family of giraffidae.

You have 28.56% of this article left to read. The following is for subscribers only.

Leave a Comment